The present invention relates to an electrical contact, and particularly to a compliant, press fit electrical contact having improved retention means.
Referring to FIG. 7, an U.S. Pat. No. 4,775,326 discloses a press fit contact comprising a mounting portion (not labeled) for mounting the press fit contact in a hole 8 defined in a printed circuit board (not shown). The wall of such a hole is normally lined with copper or the like, which is electrically connected with one or more electrical circuits of the printed circuit board. The mounting portion comprises a pair of outer legs 3, 5 and a center leg 4 between the outer legs 3, 5 which deform and press against the wall of the hole 8 when the legs 3, 4, 5 are inserted into the hole 8. The contact is retained in the hole 8 by friction between the legs 3, 4, 5 and the hole 8. However, the legs 3, 4, 5 contact the wall of the hole 8 at a limited number of points, designated as 11 and 7, which together have a limited contact area. A correspondingly large sheer stress exists at each interface between the legs 3, 4, 5 and the wall of the hole 8. Thus, the press fit contact 1 may damage the copper lining of the hole 8 during insertion, thereby reducing the electrical conduction therebetween. Furthermore, the total area of engagement of the mounting portion and the wall of the hole 8 is so small that the friction force therebetween is unreliable for retaining the contact in the hole. Therefore, over a period of usage and a number of thermal cycles, the press fit contact will yield, shift in the hole 8 and lose electrical performance, thereby affecting reliability of signal transmission.
Hence, an improved press fit contact is required to overcome the disadvantages of the prior art.
A first object of the present invention is to provide a compliant press fit contact which can be securely retained in a hole of a PCB;
A second object of the present invention is to provide a compliant press fit contact which will not damage a plated pad in a hole of a PCB during insertion into the hole.
A compliant press fit contact in accordance with the present invention comprises a retaining mounting portion for mounting the press fit contact into a metal-coated hole defined in a printed circuit board. The mounting portion is in the shape of a hollow cylinder and defines three slots extending a partial length of the mounting portion and a slit extending a full length of the mounting portion. The slots and the slit are spaced apart from each other in such fashion as to divide the mounting portion into four spring beams. Each beam has an arcuate outer surface bearing against the wall of the metal-coated hole, which elastically deforms, thereby frictionally retaining the press fit contact in the hole.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description of the present embodiment when taken in conjunction with the accompanying drawings.